<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>柱状图</title>
</head>
<style>
    #canvas {
        width: 600px;
        height: 400px;
        outline: 1px solid red;
        /* background-color: aqua; */
    }

    canvas {
        outline: 1px solid orange;
    }
</style>

<body>
    <div style="display:flex;">

        <div id="canvas"></div>
        <canvas id="barChart" height="400" width="600"> 你的浏览器不支持HTML5 canvas </canvas>
    </div>

</body>
<script src="./index.js"></script>
<script>
    let charts = new Charts({
        el: 'canvas',
        color: {
            xColor: '#999',
            yColor: '#999',
        },
        name: ['产量', '年份'],
        data: [
            [2007, 750],
            [2008, 425],
            [2009, 960],
            [2010, 700],
            [2011, 800],
            [2012, 975],
            [2013, 375],
            [2014, 775]
        ]
    })
    charts.initChart()
</script>
<script>
    function goBarChart(dataArr) {
        // 声明所需变量
        var canvas, ctx;
        // 图表属性
        var cWidth, cHeight, cMargin, cSpace;
        var originX, originY;
        // 柱状图属性
        var bMargin, tobalBars, bWidth, maxValue;
        var totalYNomber;
        var gradient;

        // 运动相关变量
        var ctr, numctr, speed;
        //鼠标移动
        var mousePosition = {};

        // 获得canvas上下文
        canvas = document.getElementById("barChart");
        if (canvas && canvas.getContext) {
            ctx = canvas.getContext("2d");
        }
        initChart(); // 图表初始化
        drawLineLabelMarkers(); // 绘制图表轴、标签和标记
        drawBarAnimate(); // 绘制柱状图的动画
        //检测鼠标移动
        var mouseTimer = null;
        canvas.addEventListener("mousemove", function (e) {
            e = e || window.event;
            if (e.layerX || e.layerX == 0) {
                mousePosition.x = e.layerX;
                mousePosition.y = e.layerY;
            } else if (e.offsetX || e.offsetX == 0) {
                mousePosition.x = e.offsetX;
                mousePosition.y = e.offsetY;
            }

            clearTimeout(mouseTimer);
            mouseTimer = setTimeout(function () {
                ctx.clearRect(0, 0, canvas.width, canvas.height);
                drawLineLabelMarkers();
                drawBarAnimate(true);
            }, 10);
        });

        //点击刷新图表
        canvas.onclick = function () {
            initChart(); // 图表初始化
            drawLineLabelMarkers(); // 绘制图表轴、标签和标记
            drawBarAnimate(); // 绘制折线图的动画
        };


        // 图表初始化
        function initChart() {
            // 图表信息
            cMargin = 30;
            cSpace = 60;
            cHeight = canvas.height - cMargin * 2 - cSpace;
            cWidth = canvas.width - cMargin * 2 - cSpace;
            originX = cMargin + cSpace;
            originY = cMargin + cHeight;

            // 柱状图信息
            bMargin = 15;
            tobalBars = dataArr.length;
            bWidth = parseInt(cWidth / tobalBars - bMargin);
            maxValue = 0;
            for (var i = 0; i < dataArr.length; i++) {
                var barVal = parseInt(dataArr[i][1]);
                if (barVal > maxValue) {
                    maxValue = barVal;
                }
            }
            maxValue += 50;
            totalYNomber = 10;
            // 运动相关
            ctr = 1;
            numctr = 100;
            speed = 10;

            //柱状图渐变色
            gradient = ctx.createLinearGradient(0, 0, 0, 300);
            gradient.addColorStop(0, 'green');
            gradient.addColorStop(1, 'rgba(67,203,36,1)');

        }

        // 绘制图表轴、标签和标记
        function drawLineLabelMarkers() {
            ctx.translate(0.5, 0.5); // 当只绘制1像素的线的时候，坐标点需要偏移，这样才能画出1像素实线
            ctx.font = "12px Arial";
            ctx.lineWidth = 1;
            ctx.fillStyle = "#000";
            ctx.strokeStyle = "#000";
            // y轴
            drawLine(originX, originY, originX, cMargin);
            // x轴
            drawLine(originX, originY, originX + cWidth, originY);

            // 绘制标记
            drawMarkers();
            ctx.translate(-0.5, -0.5); // 还原位置
        }

        // 画线的方法
        function drawLine(x, y, X, Y) {
            ctx.beginPath();
            ctx.moveTo(x, y);
            ctx.lineTo(X, Y);
            ctx.stroke();
            ctx.closePath();
        }

        // 绘制标记
        function drawMarkers() {
            ctx.strokeStyle = "#E0E0E0";
            // 绘制 y
            var oneVal = parseInt(maxValue / totalYNomber);
            ctx.textAlign = "right";
            for (var i = 0; i <= totalYNomber; i++) {
                var markerVal = i * oneVal;
                var xMarker = originX - 5;
                var yMarker = parseInt(cHeight * (1 - markerVal / maxValue)) + cMargin;
                //console.log(xMarker, yMarker+3,markerVal/maxValue,originY);
                ctx.fillText(markerVal, xMarker, yMarker + 3, cSpace); // 文字
                if (i > 0) {
                    drawLine(originX, yMarker, originX + cWidth, yMarker);
                }
            }
            // 绘制 x
            ctx.textAlign = "center";
            for (var i = 0; i < tobalBars; i++) {
                var markerVal = dataArr[i][0];
                var xMarker = parseInt(originX + cWidth * (i / tobalBars) + bMargin + bWidth / 2);
                var yMarker = originY + 15;
                ctx.fillText(markerVal, xMarker, yMarker, cSpace); // 文字
            }
            // 绘制标题 y
            ctx.save();
            ctx.rotate(-Math.PI / 2);
            ctx.fillText("产 量", -canvas.height / 2, cSpace - 10);
            ctx.restore();
            // 绘制标题 x
            ctx.fillText("年份", originX + cWidth / 2, originY + cSpace / 2 + 10);
        };

        //绘制柱形图
        function drawBarAnimate(mouseMove) {
            for (var i = 0; i < tobalBars; i++) {
                var oneVal = parseInt(maxValue / totalYNomber);
                var barVal = dataArr[i][1];
                var barH = parseInt(cHeight * barVal / maxValue * ctr / numctr);
                var y = originY - barH;
                var x = originX + (bWidth + bMargin) * i + bMargin;
                drawRect(x, y, bWidth, barH, mouseMove); //高度减一避免盖住x轴
                ctx.fillText(parseInt(barVal * ctr / numctr), x + 15, y - 8); // 文字
            }
            if (ctr < numctr) {
                ctr++;
                setTimeout(function () {
                    ctx.clearRect(0, 0, canvas.width, canvas.height);
                    drawLineLabelMarkers();
                    drawBarAnimate();
                }, speed);
            }
        }

        //绘制方块
        function drawRect(x, y, X, Y, mouseMove) {

            ctx.beginPath();
            ctx.rect(x, y, X, Y);
            if (mouseMove && ctx.isPointInPath(mousePosition.x, mousePosition.y)) { //如果是鼠标移动的到柱状图上，重新绘制图表
                ctx.fillStyle = "green";
            } else {
                ctx.fillStyle = gradient;
                ctx.strokeStyle = gradient;
            }
            ctx.fill();
            ctx.closePath();

        }


    }


    goBarChart(
        [
            [2007, 750],
            [2008, 425],
            [2009, 960],
            [2010, 700],
            [2011, 800],
            [2012, 975],
            [2013, 375],
            [2014, 775]
        ]
    )
</script>

</html>